Carbon paste biosensors

In general, biosensors contain a biological (usually polymeric) entity in the recognition environment of the sensor [166, 167]. Enzymes are the most frequently used biomodifiers, in particular, such ones that catalyze oxidation or reduction reactions (oxidoreductases), that is, oxidases and dehydrogenases, when the former ones exploit oxygen as the electron acceptor with consequent reduction to hydrogen peroxide or water. 

Electrode configurations relying on determining either O2 or H2O2 (mainly glucose sensors) are termed first-generation (hio)sensors after the first and, at present, classical construction designed by Clark and Lyons [168]. 

The first example of this kind was the bananatrode, a CPE modified with banana tissue [170] containing phenol oxidase as a catalyst for the oxidation of dopamine (DOP, a neurotransmitter), followed by a similar construction some years later [171]. Another representative is a CP-biosensor with admixed yeast containing alcohol dehydrogenase that facilitates the determination of ethanol [172]. Some biomasses such as algae, lichens, or mosses then show quite a high affinity to some heavy and precious metals with the correspondingly modified electrodes (see [4, 5,33] and references therein). 

immunochemistry with CPEs can be mentioned utilizing antibodies, antigens, and haptens in the form of the immunorecognition elements, when the antibodies are mostly immunoglobulin G, less frequently IgM [177]. Most common immunochemical analytical procedures are the competitive or sandwich assays magnetic nanoparticles being very helpful with respect to easy handling (see, e.g., [178]). 

Type of modifier Examples (specification) Purpose of modification, main principle(s) of interaction with analyte Examples References 

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J. Wang and A. Walcarius, Zeolite containing oxidase-based carbon paste biosensors. J. Electroanal. Chem. 404, 237-242 (1996). 

Wang, S.F., Xiong, H.Y., and Zeng, Q.X., Design of carbon paste biosensors based on the mixture of ionic liquid and paraffin oil as a binder for high performance and stabilization, Electrochem. Commun., 2, 807-812,2007. 

P.A. Paredes, J. Parellada, V.M. Fernandez, I. Katakis and E. Dominguez, Amperometric mediated carbon paste biosensor based on D-fructose dehydrogenase for the determination of fructose in food analysis, Biosens. Bioelectron., 12(12) (1998) 1233-1243. 

EG G PAR (USA), Model 273 A, Potentiostat/Galvanostat volt-ammetric analyzer controlled by PC equipped with a data acquisition and treatment software to record the signal generated in the electrochemical cell for DPY measurements. A 25 mL glass cell at 25°C with the carbon paste biosensor, Ag/AgCl (3.0 mol L-1 KC1) reference electrode, and a platinum wire as auxiliary electrode to perform the volt-ammetric measurements. 

Optimization of a tyrosinase carbon paste biosensor for the detection of the polyphenol quercetin... 

Fig. 6. NTE assay with tyrosinase carbon-paste biosensor.

Table 11.3 Modifying agents for carbon paste biosensors with typical examples.

A.A. Ciucu, C. Negulescu, and R.P. Baldwin, Detection of pesticides using an amperometric biosensor based on ferophthalocyanine chemically modified carbon paste electrode and immobilized bienzymatic system. Biosens. Bioelectron. 18, 303-310 (2003). 

XOD is one of the most complex flavoproteins and is composed of two identical and catalytically independent subunits each subunit contains one molybdenium center, two iron sulfur centers, and flavine adenine dinucleotide. The enzyme activity is due to a complicated interaction of FAD, molybdenium, iron, and labile sulfur moieties at or near the active site [260], It can be used to detect xanthine and hypoxanthine by immobilizing xanthine oxidase on a glassy carbon paste electrode [261], The elements are based on the chronoamperometric monitoring of the current that occurs due to the oxidation of the hydrogen peroxide which liberates during the enzymatic reaction. The biosensor showed linear dependence in the concentration range between 5.0 X 10 7 and 4.0 X 10-5M for xanthine and 2.0 X 10 5 and 8.0 X 10 5M for hypoxanthine, respectively. The detection limit values were estimated as 1.0 X 10 7 M for xanthine and 5.3 X 10-6M for hypoxanthine, respectively. Li used DNA to embed xanthine oxidase and obtained the electrochemical response of FAD and molybdenum center of xanthine oxidase [262], Moreover, the enzyme keeps its native catalytic activity to hypoxanthine in the DNA film. So the biosensor for hypoxanthine can be based on... 

S.Q. Liu and H.X. Ju, Reagentless glucose biosensor based on direct electron transfer of glucose oxidase immobilized on colloidal gold modified carbon paste electrode. Biosens. Bioelectron. 19, 177-183 (2003). 

Q.L. Wang, G.X. Lu, and B.J. Yang, Hydrogen peroxide biosensor based on direct electrochemistry of haemoglobin immobilized on carbon paste electrode by a silica sol-gel film. Sens. Actuators, B Chem. 99, 50-57 (2004). 

Q. Yao, S. Yabuki and F. Mizutani, Preparation of a carbon paste/alcohol dehydrogenase electrode using polyethylene glycol-modified enzyme and oil-soluble mediator, Sens. Actuators B Chem., 65(1-3) (2000) 147-149. A. Morales, F. Cespedes, E. Martinez-Fabregas and S. Alegret, Ethanol amperometric biosensor based on an alcohol oxidase-graphite-polymer biocomposite, Electrochim. Acta, 43(23) (1998) 3575-3579. 

S.L. Alvarez-Crespo, M.J. Lobo-Castanon, A.J. Miranda-Ordieres and P. Tunon-Blanco, Amperometric glutamate biosensor based on poly(o-phenylenediamine) film electrogenerated onto modified carbon paste electrodes, Biosens. Bioelectron., 12(8) (1997) 739-747. 

L. Agiif, J. Manso, P. Yanez-Sedeno and J.M. Pingarron, Amperometric biosensor for hypoxanthine based on immobilized xanthine oxidase on nanocrystal gold-carbon paste electrodes, Sens. Actuators B, 113(1) (2006) 272-280. 

S. Hu, C. Xu, J. Luo, J. Luo and D. Cui, Biosensor for detection of hypoxanthine based on xanthine oxidase immobilized on chemically modified carbon paste electrode, Anal. Chim. Acta, 412(1-2) (2000) 55-61. 

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